Klaw is right but the rate sucks. If something is $10 Mxn most places will accept $1 US, or a 10:1 exchange rate. Today's bank rate is $10.76 so even 10:1 is not a good deal. But the ADO rate for paying in dollars is considerably less than 10 to 1 even. But yes, as Klaw says, you can pay with US Dollars. I believe the rate the other day for the ADO service to downtown from the aiport was $35 pess, or $4 US.